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your model class by extending the RealmObject public class Dog extends RealmObject { @PrimaryKey private int id; @Required // Name cannot be null private String name; private int age; // ... Generated getters and setters ... }
dog = new Dog(); dog.setName("Rex"); dog.setAge("1"); // Get a Realm instance Realm realm = Realm.getDefaultInstance(); // Persist your data easily realm.beginTransaction(); realm.copyToRealm(dog); realm.commitTransaction();
= Realm.getDefaultInstance(); // Create and persist your data easily realm.beginTransaction(); Dog dog = realm.createObject(Dog.class); dog.setName("Rex"); dog.setAge("1"); realm.commitTransaction();
dogs who are named "Fido" or "Snoopy" RealmResults<Dog> puppies = realm.where(Dog.class) .equalTo("name", "Fido") .or() .equalTo("name", "Snoopy") .findAll();
= realm.where(Dog.class); // Add query conditions: query.equalTo("name", "Fido"); query.or().equalTo("name", "Odie"); // Execute the query: RealmResults<Dog> result1 = query.findAll(); // Or do the same all at once (the "Fluent interface"): RealmResults<Dog> result2 = realm.where(Dog.class) .equalTo("name", "Fido") .or() .equalTo("name", "odie", Case.INSENSITIVE) .findAll();
to get notified when the object is updated. d1.registerChangeListener(new RealmChangeListener() { @Override public void onChange() { // called once the query complete and on every update // do something now that the obj is updated } }); // assume code below is in some other thread/etc (Android Service, AsyncTask, etc) // Retrieve the same dog as above Dog d2 = realm.where(Dog.class).equals("id", 123).first(); realm.beginTransaction(); d2.setAge(12); realm.commitTransaction(); // d2s change listener gets called after the commit.*
RealmChangeListener() { @Override // Gets called any time any object that this query represents gets updated public void onChange() { // do something with the updated results } }); // in some other thread realm.beginTransaction(); Dog pup = realm.createObject(Dog.class); pup.setName("Snoop"); pup.setAge(1); realm.commitTransaction(); // At this piont the puppies change listener will be invoked as the query // results have automatically been updated.
// Set up with the config byte[] key = new byte[64]; new SecureRandom().nextBytes(key); RealmConfiguration config = new RealmConfiguration.Builder(context) .encryptionKey(key) .build(); // Realm data is now encrypted Realm realm = Realm.getInstance(config);
randomly pass Realm objects between threads. If you need the same data on another thread you just need to query for that data on the that other thread. Furthermore, you can observe the changes using Realms reactive architecture. Remember - all objects are kept up to date between threads - Realm will notify you when the data changes. — Realm Docs
is that Realm makes it effortless to work with data on multiple threads without having to worry about consistency or performance because objects and queries are auto-updating at all times. — Realm Docs
Non-trivial multi- threaded programs are incomprehensible to humans.1 — Edward A Lee PHD Berkeley University of California 1 The Problem with Threads PDF Link
an empty list at this point (query is running in the BG) dogs.addRealmChangeListener(new RealmChangeListener() { @Override public void onChange() { // called once the query completes and on every update // do something with the query results } }); // As soon as the query completes the change listerner will be notified // that the results are available (and will continue to get notified) // of new updates // Working with a single object query Dog dog = realm.where(Dog.class).equalTo("age", 2).findFirstAsync(); dog.addRealmChangeListener(new RealmChangeListener() { @Override public void onChange() { // called once the query completes and on every update // do something with the dog object } });
// => 0 - No puppies in the Realm DB // Query and update the result asynchronously in another thread realm.executeTransactionAsync(new Realm.Transaction() { @Override public void execute(Realm realm) { // begin & end transcation calls are done for you. Dog theDog = realm.createObject(Dog.class); theDog.setAge(3); // You could also query and alter objects as well } }, new Realm.Transaction.Callback() { @Override public void onSuccess() { // Original Queries and Realm objects are automatically updated. puppies.size(); // => 1 because there is one puppy now } });
syntax for brevity) // Load all persons and merge them with their latest stats from GitHub (if they have any) Realm realm = Realm.getDefaultInstance(); GitHubService api = retrofit.create(GitHubService.class); realm.where(Person.class).isNotNull("username").findAllAsync().asObservable() .filter(persons.isLoaded) .flatMap(persons -> Observable.from(persons)) .flatMap(person -> api.user(person.getGithubUserName()) .observeOn(AndroidSchedulers.mainThread()) .subscribe(user -> showUser(user)); EXAMPLE APP - HTTP://BIT.LY/REALM-RXJAVA
new RealmMigration() { @Override public void migrate(DynamicRealm realm, long oldVersion, long newVersion) { // DynamicRealm exposes an editable schema RealmSchema schema = realm.getSchema(); // Migrate to version 1: Add a new class. // Example: // public Person extends RealmObject { // private String name; // private int age; // // getters and setters left out for brevity // } if (oldVersion == 0) { schema.create("Person") .addField("id", long.class, FieldAttribute.PRIMARY_KEY) .addField("name", String.class) .addField("age", int.class); oldVersion++; } } } // in your init RealmConfiguration config = new RealmConfiguration.Builder(context) .schemaVersion(1) // Must be bumped when the schema changes .migration(new MyMigration()) // Migration to run instead of throwing an exception .build()
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